1st ibmo - colombia 1985./q6
Source: Spanish Communities
April 6, 2006
Columbiageometrycircumcircletrigonometrygeometry unsolved
Problem Statement
Given an acute triangle , let , and be points in the lines , and respectively. If the lines , and pass through the centre of the circumcircle of the triangle , whose radius is , show that:
\frac{1}{AD}\plus{}\frac{1}{BE}\plus{}\frac{1}{CF}\equal{}\frac{2}{R}